The pain of your divorce is not yours alone. Parents feel like a failure if their children divorce.. that they're at fault. They have their own fear of losing their relationship with you, losing touch with their grandchildren/nieces, nephews. They are deeply hurt. They have their own grief to work through. But they have good friends who can listen. Having that final cry is putting your mother-in-law in a sticky situation.. and not a good one either. It's different if she has an emotional meltdown with you. This was a child of her womb. But even that is dicey.
I found I had to forge a ..not new... but different relationship with my former in-laws. I was consistent early on to keep saying that I'd like to have a relationship with them (sisters and mom) but that I understood and did not want to come in the way of their relationship with their brother/son. It helped immensely that my mother-in-law told her daughters that I'd been a member of the family for 25 years and that I still was.
My mother-in-law and I don't talk about him. My sisters-in-law will talk about him to vent. Over time I've learned to listen a bit, not take things personally then subtly change the subject to something else. Hearing about him, especially in the most painful times did nothing positive for me. Yet I realize they have their own pain.. but it doesn't have to be mine.
The former spouse blamed me for everything that ever went wrong, still does. I was thankful during the painful time that he didn't take any responsibility because no one can do the wrong thing 100% of the time!
Good job on getting out of the self medicated blur. The good and bad of that is that you experience the feelings of loss but in a way that leads to growth and healing.
A suggestion... stop capitalizing them.. She, The Happy Couple... etc. It's giving like deferring to their eminence.. like you'd refer to the pope or royal couple.
Why did he leave a relationship you felt was great? Who knows.. and you never will. But goodness me, he's gone out of his way to prove he's done (and probably has been for a while).
In my case I still desperately wanted a relationship as parents but he didn't/couldn't based on her needs. So he moved in immediately with her (joint account and all)two weeks after the bomb, got married about 3 months after the divorce was final and are now welcoming a baby after a year and a half of marriage.
And you know what? It's none of my business.. nor do I want it to be. Babies are miracles, deserve all the love possible. And he's not my husband. My emotional wellbeing is not forefront in his mind. He's a guy who's neglects his children and pays the alimony/support on time.
It's a very tough time. You're doing all the right things. Keep going and showing that incredible aver you are.
